mysql - 对来自不同列和计数的值进行分组

Question

我有这张桌子：

UNIQUE_ID | WINNER_ID | FINALIST_ID
________1 | ________1 | __________2
________2 | ________1 | __________3
________3 | ________3 | __________1
________4 | ________1 | __________2

我需要一份所有选手（获胜者和决赛选手）的名单，以及他们获得第一或第二名的次数。

在这种情况下，它将是：

PLAYER_ID | WINNER_TIMES | FINALIST_TIMES
________1 | ___________3 | _____________1
________2 | ___________0 | _____________2
________3 | ___________1 | _____________1

这里已经提出了一个类似的问题（LINK），但我不明白答案。

Answer 1

select  coalesce(winner_id, finalist_id) as PLAYER_ID
,       count(winner_id) as WINNER_TIMES
,       count(finalist_id) as FINALIST_TIMES
from    (
        select  winner_id
        ,       null as finalist_id
        from    YourTable
        union all
        select  null
        ,       finalist_id
        from    YourTable
        ) as SubQueryAlias
group by
        coalesce(winner_id, finalist_id)

SQL Fiddle 上的实时示例。

Answer 2

试试这个 ：：

 Select 
    user_id as user, 
    winner_temp.count(1) as winning_count
    finalist_temp.count(1) as runner_up_count
    from
    user_table 
    left join 
    (Select winner_id, count(1) from table group by winner_id) as winner_temp on (user_table.user_id = winner_temp.winner_id)
    left join 
    (Select finalist_id, count(1) from table group by finalist_id) as finalist_temp on 
    (user_table.user_id = finalist_temp.finalist_id)